The KID Foundation's SPD Network. Includes a national resource directory where parents can access local physicians, occupational therapists, mental health professionals, educators, facilities, community resources, and more. (Health care providers who work with SPD are encouraged to register here, as well.)

We were rushing to an appointment, hustling along a crowded sidewalk on a humid summer day. I was cautioning Elisabeth about something, dragging her behind me the way you sometimes do with an almost-4-year-old. The traffic was loud and smelled of exhaust, a kid on a bike was blowing a whistle, and the storefronts were bursting with bright vegetables and flowers.

Suddenly, my daughter stopped in her tracks and screamed — a long, loud scream of agony and frustration — prompting everyone around us to turn and glare. Later, when I asked her why she screamed, she said she didn’t know, she just couldn't control the impulse.

There was more. Elisabeth was terrified of playground swings and of walking barefoot in grass. She hated crowds and washing her hair. But these I chalked up to developmental angst. I knew almost nothing about sensory integration (SI). Only when Elisabeth was evaluated, at age 5, as having Sensory Processing Disorder (SPD) by an occupational therapist trained in SI, did I begin to understand her perplexing behaviors.

I remember another day, too, about two years later. Sitting in our school district’s offices with the "special education committee" assigned to evaluate my daughter’s needs, I became furious as the psychologist — who had never seen my daughter — pronounced her symptoms as "clearly ADHD," on the basis of a checklist she held in her hands. She was as dismissive of SPD (also known as SI dysfunction) as I was of ADD/ADHD, each of us refusing to entertain the possibility that the other’s diagnosis was correct.

As it turns out, my daughter has both. But it took another year or so for me to learn the similarities and differences in the two conditions, or comorbidities, and to accept treatment for ADHD. Examine their symptoms side by side, and you’ll see some striking parallels, as well as several disparities. The two conditions don’t necessarily go hand in hand, but they often do. “Many neurological problems overlap,” explains educator Carol Stock Kranowitz, author of The Out-of-Sync Child: Recognizing and Coping with Sensory Integration Dysfunction. “Often, a child who has dysfunction in one area will have dysfunction in others.”

The correlation of ADD/ADHD and SPD symptoms is shown by a new national study of children ages 2 to 21 done at the University of Colorado. Parents reported that, of children who showed symptoms of either ADD/ADHD or SPD, 40% displayed symptoms of both, according to Lucy Jane Miller, Ph.D., director of the Sensory Processing Treatment and Research (STAR) Center at the Children’s Hospital in Denver. When ADHD and SPD do coexist, however, it’s important to distinguish one from the other because their treatments are different.

What is SI?

Sensory integration is the process by which information from our senses (touch, sight, hearing, taste, smell, as well as balance) is interpreted by the brain so that we can respond appropriately to our environment. A child with good SI automatically filters the important from the unimportant stimuli as she makes her way through the world. At school, she sits alert at her desk without thinking about her posture. She pays attention to the teacher and filters out the noise of children in the hallway. On the street, she ignores the booming car radios and honking horns, and the itch of her wool sweater, but attends to the sound of the bus turning the corner, “telling” her to wait before crossing the street.

For some children with sensory processing disorder, information reaching the senses often feels like an assault of competing stimuli. To get the idea, imagine this scenario: Three children are telling you conflicting stories about who had the toy, the phone is ringing, and you suddenly smell the cake burning in the oven — and did I mention the itchy rash on your legs?

For others, outside stimuli are dulled, as if a shade has been pulled over the environment, muting sights, sounds, and touch. These children crave extra stimulation to arouse themselves — similar to needing the jolt of a wake-up shower after a sleepless night. These are the kids who love to spin and swing upside down. Most children with SPD display elements of both extremes, suffering from sensory overload at some times, seeking stimulation at others. It’s not difficult to see how the symptoms — distractibility, the need for intense activity, problems with social interactions — could seem like ADHD.

A child playing in a sandbox can ignore the sweat trickling down her face and neck because she loves the sandbox, and there’s a breeze to cool her off a little. A child with SPD cannot ignore anything — the sweat is distracting and irritating, and the wind makes her feel worse, not better. Lacking an inner ability to cope with these irritations, she may kick the sand in frustration and lash out at her playmates, ruining her playtime and her entire afternoon. The bad feelings stay with her long after the physical triggers are gone. Children with SPD can be frustrating to parents and teachers, but their behavior is most frustrating to the children themselves. A. Jean Ayres, the groundbreaking occupational therapist who first described SI dysfunction more than 40 years ago, likened it to having
“a traffic jam in the brain.”

Who’s at risk?

Most people develop normal sensory functioning, but some experts believe that the process goes awry in as many as 10% of children. As with ADD/ADHD, the causes can be unclear and may be genetic, but there are extrinsic factors that may put children at particular risk for SPD. These include maternal deprivation, premature birth, prenatal malnutrition, and early institutional care. Bundling, minimal handling, and propping bottles for feeding deprive the infant of the kinds of stimulation that promote integration of the senses. Such factors may explain why the incidence of SPD is higher among children who were adopted from orphanages. Repeated ear infections before age 2 may also increase the risk factor.